Spotlight failure effect in exogenous orienting.

Many experimental results about spatial attention have been explained by assuming the existence of an attentional "spotlight" which can move from one location in visual space to another. Such an account has been recently challenged by findings which show the influence of nonspatial factors in spatial attention. In particular, the so-called "spotlight failure" effect refers to the influence of the probability of occurrence of different stimuli. However, such an effect has only been reported in the case of endogenous (or central) orientation, rather than on exogenous (or peripheral) orienting. We present evidence showing that the spotlight failure effect can be obtained with exogenous orienting, even at a short SOA (100 ms). Besides, experimental instructions can modulate the effect, which agrees with theoretical accounts proposing that top-down factors can influence attentional capture.     

Objects and their locations in exogenous cuing

Anatomical, physiological, and behavioral studies provide support for separate object- and locationbased components of visual attention. Although studies of object-based components have usually involved voluntary attention, more recent evidence has suggested that objects may play an independent role in reflexiveexogenous orienting, at least at long stimulus onset asynchronies (SOAs). In the present experiments, the role of objects in reflexive attentional orienting was investigated by developing a task in which location and object cuing could be separately examined for both short and long SOAs. Typical location cuing effects were obtained, indicating facilitation at short cue—target intervals and inhibition of return (IOR) at longer intervals. In contrast, object cuing resulted in facilitation for cued objects at long cue—target intervals and no object-based IOR. Interestingly, object cuing primarily affected targets at cued locations, and not those at uncued locations. Together, the experiments examine the interactive nature of objects and locations in exogenous orienting and seem most consistent with a location-mediated view of object-based orienting.     

Objects and their locations in exogenous cuing.

Anatomical, physiological, and behavioral studies provide support for separate object- and location-based components of visual attention. Although studies of object-based components have usually involved voluntary attention, more recent evidence has suggested that objects may play an independent role in reflexive exogenous orienting, at least at long stimulus onset asynchronies (SOAs). In the present experiments, the role of objects in reflexive attentional orienting was investigated by developing a task in which location and object cuing could be separately examined for both short and long SOAs. Typical location cuing effects were obtained, indicating facilitation at short cue-target intervals and inhibition of return (IOR) at longer intervals. In contrast, object cuing resulted in facilitation for cued objects at long cue-target intervals and no object-based IOR. Interestingly, object cuing primarily affected targets at cued locations, and not those at uncued locations. Together, the experiments examine the interactive nature of objects and locations in exogenous orienting and seem most consistent with a location-mediated view of object-based orienting.     

Endogenous versus exogenous attentional cuing effects on memory

Three experiments were conducted to investigate the influence of early attentional cuing effects on subsequent memory. In an incidental study phase, a cue preceded two simultaneously displayed words. An endogenous cue (row of arrows pointing toward one word) or an exogenous cue (row of stars at the location of one word) indicated which word to read aloud. In a subsequent test phase, memory for these cued and uncued words was measured. In Experiment 1, these attentional manipulations had almost no effect on subsequent implicit memory measured using a speeded reading (naming) test. Experiments 2 and 3 demonstrated that, on an explicit memory test, words were reliably better recognized in the endogenous condition than in the exogenous condition. These results suggest that endogenous attentional cues promote more active processing and hence elaboration of words, assisting their subsequent conscious retrieval.     

The development of exogenous orienting: mechanisms of control

The present study examined exogenous orienting in children ages 6 years (n=14), 10 years (n=13), 14 years (n=14), and adults (n=13). The main purpose was to identify which of the attentional operations underlying exogenous orienting (disengaging, shifting, and/or engaging) improves with age. A simple detection task was used in which single targets were correctly (80%) or incorrectly (20%) cued. The main finding was that disengaging attention alone distinguished the performance of younger children from that of older children and adults, regardless of whether attention alone (covert attention) or attention and associated sensory and motor systems (overt attention) were involved. In addition, our data, in contrast to those reported previously, raise the possibility that even the youngest children tested were able to use the predictability of the cue to enhance their performance. These and related neuroanatomical findings are taken as evidence for the development with age of more flexible control in orienting visual attention.     

Audiovisual links in exogenous covert spatial orienting

Subjects judged the elevation (up vs. down, regardless of laterality) of peripheral auditory or visual targets, following uninformative cues on either side with an intermediate elevation. Judgments were better for targets in either modality when preceded by an uninformative auditory cue on the side of the target. Experiment 2 ruled out nonattentional accounts for these spatial cuing effects. Experiment 3 found that visual cues affected elevation judgments for visual but not auditory targets. Experiment 4 confirmed that the effect on visual targets was attentional. In Experiment 5, visual cues produced spatial cuing when targets were always auditory, but saccades toward the cue may have been responsible. No such visual-to-auditory cuing effects were found in Experiment 6 when saccades were prevented, though they were present when eye movements were not monitored. These results suggest a one-way cross-modal dependence in exogenous covert orienting whereby audition influences vision, but not vice versa. Possible reasons for this asymmetry are discussed in terms of the representation of space within the brain.     

Interaction between endogenous and exogenous orienting in crossmodal attention

Using a cue-target paradigm, we investigated the interaction between endogenous and exogenous orienting in cross-modal attention. A peripheral (exogenous) cue was presented after a central (endogenous) cue with a variable time interval. The endogenous and exogenous cues were presented in one sensory modality (auditory in Experiment 1 and visual in Experiment 2) whereas the target was presented in another modality. Both experiments showed a significant endogenous cuing effect (longer reaction times in the invalid condition than in the valid condition). However, exogenous cuing produced a facilitatory effect in both experiments in response to the target when endogenous cuing was valid, but it elicited a facilitatory effect in Experiment 1 and an inhibitory effect in Experiment 2 when endogenous cuing was invalid. These findings indicate that endogenous and exogenous cuing can co-operate in orienting attention to the crossmodal target. Moreover, the interaction between endogenous and exogenous orienting of attention is modulated by the modality between the cue and the target.     

On the spatial metric of short-SOA costs of exogenous cuing

When the stimulus onset asynchrony (SOA) between the cue and the target is short, exogenous spatial cues usually produce a response time benefit. However, consistent with several recent studies, we have found that a short stimulus onset asynchrony is not sufficient. At least one more factor--the number of cue and target locations--also plays a role. Even more interesting, when 8 cue and target locations are used, the effect of an exogenous cue produces a cost on valid cue trials, and the spatial metric of this negative cuing effect depends on whether the cue remains visible at target onset.     

The effect of cuing after backward conditioning trials

Rats were given backward pairings of a tone (CS) and shock (US) and were then tested for response to the CS in a lick suppression test. Animals given a cuing or reminder treatment prior to the test exhibited enhanced suppression in the presence of the tone relative to a variety of control conditions. The cue-induced suppression enhancement did not appear to result from sensitization or short-term motivational changes nor did it seem to depend on second-order conditioning of the test context. The effect appeared more robust as the number of backward conditioning trials preceding the cue increased. The results were discussed in terms of current explanations of backward conditioning effects.     

The effect of orienting tasks on recognition memory

The effect of orienting tasks on recognition memory for words and faces was investigated. It was found that relevant orienting tasks improved recognition memory for both classes of stimuli compared with a nonrelevant orienting task and the control condition of testing recognition memory without an orienting task. Attention is drawn to the possibility of qualitative differences between recall and recognition for the effect of orienting tasks. The findings are related to recognition theories. It is suggested that the findings lend support to those theories which hold that retrieval processes play a major role in recognition memory.     

Competition between endogenous and exogenous orienting of visual attention

The relation between reflexive and voluntary orienting of visual attention was investigated with 4 experiments: a simple detection task, a localization task, a saccade toward the target task, and a target identification task in which discrimination difficulty was manipulated. Endogenous and exogenous orienting cues were presented in each trial and their validity was manipulated orthogonally to examine whether attention mechanisms are mediated by separate systems and whether they have additive and independent effects on visual detection and discrimination. The results showed that each orienting mechanism developed its typical and independent effect in every case except for the difficult identification task. A theoretical framework for understanding the relationship between endogenous and exogenous orienting of attention is proposed, tested, and confirmed.     

Competition in early exogenous orienting between 7 and 21 weeks

Exogenous (stimulus-driven) orienting between 7 and 21 weeks of age was examined in 2 experiments using a display with multiple potential targets of attention. On each trial a small moving probe was used to draw attention to one side of the display or the other. This moving probe appeared simultaneously with 27 static bars. In the first experiment, sensitivity to the moving target was affected significantly by the spatial distribution of these red and green static bars for 14-week-olds but not for 8-week-olds. Sensitivity to the moving target was lower for 14-week-olds when most of the red bars appeared contralaterally to the moving target. This effect replicated a similar effect observed in J. L. Dannemiller (1998). The lack of a contralateral competition effect in Experiment 1 for the 8-week-olds may have occurred because I used a stronger motion stimulus for the younger infants in an attempt to hold the overall performance constant at the 2 ages. A second experiment using a weaker motion stimulus showed that this contralateral competition effect was observable over the entire age range from 7 to 21 weeks of age. Thus as early as 7 weeks of age, sensitivity for a small moving stimulus can be significantly influenced by the simultaneous presence of competing targets of attention in the visual field. Large increases in overall sensitivity were also found across the age range from 7 to 21 weeks. Results are discussed in terms of the development of putative competition mechanisms involved in exogenous orienting.     

Orienting in space and time: Joint contributions to exogenous spatial cuing effects

We examined whether the time course of exogenous spatial-cuing effects is sensitive to the allocation of attention in time. Expectation for a target within a particular time window following the cue was manipulated by varying the proportion of trials that appeared at each of three stimulus onset asynchronies in both a detection task and a two-alternative forced-choice discrimination task. The time course of spatial-cuing effects was sensitive to the temporal expectation manipulation only in the discrimination task. The results are discussed with reference to the role of attentional set in exogenous spatialcuing paradigms.     

An apparent-motion confound causes the negative exogenous cuing effect at SOAs with larger numbers of target locations

Salient but irrelevant stimuli seem to cause an automatic orienting of covert attention, facilitating the detection of targets at the cued location for a brief period of time. However, this finding is highly dependent on the number of possible target locations, at least when the simple detection of targets is all that the task requires. Whereas small numbers of possible target locations (e.g., 2 or 3) produce the well-known advantage in response time for valid cue trials (i.e., a positive cuing effect), larger numbers of possible target locations (e.g., 6 or 8) produce a negative cuing effect. If not explained in terms of a nonattentional mechanism, this latter finding raises serious questions about the standard interpretation of positive cuing effects. The present experiment tested a particular nonattentional mechanism: that a confound between target presence and apparent motion, which occurs only on invalid cue trials, is responsible for negative cuing effect. We reduced or eliminated this confound by the use of a new type of catch trial and eliminated the negative cuing effect with large numbers of target locations.     

物体拓扑性质对背景线索效应的影响及其加工机制

背景线索效应是指在视觉搜索中由于场景的重复曝光而产生的行为便利。而以往研究关注于刺激的欧式性质所代表的属性信息对背景线索效应的影响, 然而在视知觉加工过程中扮演重要角色的拓扑性质对背景线索效应的影响仍缺乏相关实证研究。因此, 研究采用视觉搜索任务, 通过操控不同场景中刺激的拓扑性质或欧式性质的变化, 考察拓扑性质与欧式性质两种属性信息对背景线索效应的调制。结果发现：(1)拓扑性质和欧式性质与目标之间的联结关系均可促进行为反应, 获得背景线索效应; (2)视觉学习机制对拓扑性质的重复性更加敏感, 并且拓扑性质与目标之间联结关系的稳定性相对于欧式性质与目标之间的联结关系稳定性对于背景线索效应的获得具有更为重要的意义。     

编码后奖赏影响基于议程的学习：奖赏预期和结果的作用

基于ABR模型考察奖赏预期和奖赏结果对不同难度词对记忆与元记忆的影响。结果发现：(1)限时学习条件下,奖赏结果促进不同难度词对记忆成绩和学习判断,奖赏预期仅提高简单词对的记忆成绩。(2)自定步调学习条件下,定时学习判断时奖赏结果仅影响学习判断;奖赏预期促进高难度词对的学习时间分配,从而提高记忆成绩和学习判断。(3)在自定步调学习时,奖赏预期超越难度成为影响学习时间分配的因素。以上结果表明,个体会综合奖赏预期、奖赏结果和难度构建学习议程,足够大的奖赏预期会超越难度成为议程构建的主导因素。但奖赏预期和奖赏结果对记忆成绩、学习时间分配和学习判断的影响受学习条件调节。     

Assessing the automaticity of the exogenous orienting of tactile attention

We examined whether or not abrupt tactile onsets are capable of exogenously capturing tactile spatial attention when visual spatial attention is focused elsewhere. In experiment 1, we compared performance under dual-task conditions (where participants performed a tactile exogenous cuing task and a rapid serial visual presentation--RSVP--task at the same time) with their performance under single-task conditions (where the participants had to perform only the cuing task, although the RSVP stream was still presented in the background) and to a no-stream condition (where only the cuing task was presented). Tactile cuing was completely suppressed in both the dual-task and single-task conditions, showing that exogenous tactile spatial orienting is modulated by visual-spatial attention, which hence appears to be far from truly automatic. In experiment 2, we demonstrated that the abolishment of exogenous tactile orienting was not caused by the transient presentation of abrupt onset stimuli (letters). These results therefore show that exogenous spatial attentional orienting toward abrupt peripheral tactile stimuli is possible as long as perceptual resources are not depleted by a perceptually demanding (RSVP) task.     

Effects of spatial cuing on the onset repulsion effect

Effects of cuing the onset (initial) location of a moving target on memory for the onset location of that target were examined. If a cue presented prior to target onset indicated the location where that target would appear, the onset repulsion effect (in which the judged initial location of the target was displaced in the direction opposite to target motion) was decreased, and the onset repulsion effect was smaller if the cue was valid than if the cue was invalid. If a cue presented during target motion or after the target vanished indicated the location where that target had appeared, the onset repulsion effect was eliminated. The data (1) suggest that positional uncertainty might contribute to the onset repulsion effect, (2) provide the first evidence of an effect of expectancy regarding target trajectory on the onset repulsion effect, and (3) are partially consistent with previous data involving effects of attention and spatial cuing on the Fröhlich effect and on representational momentum.